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Plasticization Effect (plasticization + effect)
Selected AbstractsPolypropylene/clay nanocomposites prepared by in situ grafting-melt intercalation with a novel cointercalating monomerJOURNAL OF APPLIED POLYMER SCIENCE, Issue 1 2008Pingan Song Abstract Polypropylene (PP)/clay nanocomposites were prepared by melt-compounding PP with organomontmorillonite (OMT), using maleic anhydride grafted polypropylene (PP- g -MA) as the primary compatibilizer and N -imidazol- O -(bicyclo pentaerythritol phosphate)- O -(ethyl methacrylate) phosphate (PEBI) as the cointercalating monomer. X-ray diffraction patterns indicated that the larger interlayer spacing of OMT in PP was obtained due to the cointercalation monomer having a large steric volume and the d -spacing further increased with the addition of PP- g -MA, as evidenced by transmission electron microscopy. Thermogravimetric analysis revealed that the PEBI-containing PP nanocomposites exhibited better thermal stability than PEBI-free PP composites. Dynamic mechanical analysis demonstrated that the storage modulus was significantly enhanced, and the glass transition temperature (Tg) shifted slightly to low temperature with the incorporation of clay for PP/OMT hybrids. PEBI-containing PP/OMT composites gave a lower Tg value because of the strong internal plasticization effect of PEBI in the system. Cone calorimetry showed that the flame-retardancy properties of PP nanocomposites were highly improved with the incorporation of PEBI. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source] Characteristics and oil absorption of deep-fat fried dough prepared from ball-milled wheat flourJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 3 2009Pariya Thanatuksorn Abstract BACKGROUND: High levels of oil in fried products has been recognized as causing health problems. The formation of microstructure during frying is one factor that influences oil absorption. Above the glass transition temperature (Tg), the physical properties of a polymer influences the formation of structure. The ball-milling process changes the physicochemical properties of wheat flour constituents. The present study investigated the effects of physicochemical changes in wheat flour by the ball-milling process on structure formation and oil absorption in wheat flour dough model. RESULTS: Dough samples were made from wheat flour that had been ball-milled for 0 to 10 h and then fried in frying oil at 150 °C for 1,7 min. Thermal properties of wheat flour, structure alteration, and textural properties of fried samples were evaluated. As compared with samples made of non-milled flour, samples made from milled flour had smaller pores and higher oil absorption. The fracture force of a fried sample prepared from non-milled flour was lower than that of a sample prepared from milled flour. CONCLUSION: Ball-milling affected the microstructure formation in fried wheat flour dough, and subsequently oil absorption. The crispness of a sample prepared from non-milled wheat flour is higher than that of a sample prepared from ball-milled wheat flour. This may be due not only to a plasticization effect, but may also be dependent on microstructure. Copyright © 2008 Society of Chemical Industry [source] Dendronized Polymers via Macromonomer Route in Supercritical Carbon DioxideMACROMOLECULAR RAPID COMMUNICATIONS, Issue 19 2008Liborio Ivano Costa Abstract Radical polymerizations from third to fifth generation macromonomers were conducted in supercritical carbon dioxide (scCO2). It was found that all monomers were not soluble in such a medium, and reactions occurred in the CO2 -swollen monomer matrices. Despite the expected severe diffusion limitations, very high conversions and molecular weights were obtained. It is believed that the plasticization effect induced by the CO2 plays a key role in these surprising findings. Scanning force microscopical analyses confirmed that mainly linear dendronized polymers were obtained and therefore chain transfer to polymer is virtually irrelevant. [source] Hyperbranched polymers in cationic photopolymerization of epoxy systemsPOLYMER ENGINEERING & SCIENCE, Issue 8 2003M. Sangermano Mixtures of epoxy resins in the presence of epoxy hyperbranched polymers (HBP), in the range of 5,15 wt%, were investigated in the cationic photocuring process. No significant differences in rate of polymerization or final epoxy groups conversion were observed. At low concentration, HBP acts as plasticizer and causes a decrease of the glass transition temperature of the epoxy matrix and of the E, value. At higher concentration (about 15 wt%), two Tg values are evident, indicating a biphasic structure of the system. The SEM analysis of the fracture surface of the samples confirms a particulate structure with separate HBP domains interconnected to the epoxy matrix. In all the samples investigated, a clear increase of the impact resistance was observed, resulting either from the plasticization effect or from the particulate structure induced by the presence of the HBP resin. [source] | ||||||||||